Monday, September 21, 2009

World Wide Reactor Deployment

Scientists of the Reactor Physics Group at Laboratoire de Physique Subatomique et de Cosmologie, Grenoble, France, together with Sylvain David have made important contributions to Molten Salt Reactor technology during this decade. They are among the most important and far reaching energy thinkers in the world, yet outside of the narrow circle found in the Energy from Thorium Discussion Forum, their work is almost unknown in the United States. I am posting "Molten Salt Reactors and Possible Scenarios for Future Nuclear Power Deployment as a means of further enhancing the intellectual legitimacy of the Energy from Thorium approach to climate change mitigation, and to further enhance American Awareness of the work of the LPSC on Molten Salt technology. LPSC researchers use the term Thorium Molten Salt Reactor. This term might be considered the European equivalent of the Liquid Fluoride Thorium Reactor (LFTR).

I have referred to the work of the Reactor Physics Group in other posts, but I want to make their very important work on the world wide deployment of post-carbon nuclear power. What follows is a brief summery of the RPG model for world Wide Nuclear Deployment.

Nuclear Power Deployment Scenarios

The worldwide demand for primary energy is constantly increasing and, if it is to be satisfied, solutions must be thought out and the extent to which the responses are adapted to the issue must be examined. There are not so many options once it is agreed that recourse to fossil energies should be as reduced as possible in order to limit green house gas emissions.

Fission based nuclear energy is, along with new renewable energies and, in the longer run, fusion based energy, one of the primary energy sources capable of contributing significantly to satisfying the demand.

The scenarios studied in our group show the potential, and limitations, for a worldwide deployment of nuclear power, and demonstrate that the different reactor types are quite complementary. This study shows that fissile matter availability comes as a strong constraint if a fleet of reactors able to breed their own fuel is to be started. In addition, such breeder reactors will not be deployed industrially before the next 20 to 25 years so that any transition towards extensive and sustainable nuclear power production will have to call on second or third generation light water reactors, which will have to be built.

We have considered three main reactor types:

Pressurized water reactors of the second generation (PWR) and third generation (EPR - European Pressurized Reactor). These reactors do not breed their fuel. PWRs are currently in operation while EPRs will begin production in 2010 in our scenarios.

Fast neutron reactors with a liquid metal coolant (FNR). These are fourth generation reactors that are based on the 238U/Pu fuel cycle. Their breeding ratio varies with the scenario considered. FNRs begin production in 2025 in our scenarios.

Molten salt reactors (MSR). These are fourth generation reactors based on the232Th/ 233Ufuel cycle, with a neutron spectrum that can be anything from thermal to fast. These begin production in 2030 in our scenarios.

Our studies show that an intensive nuclear power deployment is feasible but that it requires careful handling of fissile matter resources and of nuclear wastes. The scenario that combines the three reactor types is by far the one that gives the most flexibility in the deployment of nuclear power; if necessary, it could accommodate more intensive production than we have set in our scenarios. The three reactor types complement each other strikingly; the use of natural fissile matter is optimized (figure 3); the volume of trans-uranians produced is minimal; the option to stop, then restart nuclear power production remains open so that decisions are not irreversible. Intermediate scenarios, with a greater or lesser contribution of FNRs as compared to MSRs can be considered in order to satisfy regional or other criteria but, with these studies, it appears that the 232Th/ 233U fuel cycle will be needed early on.

Figure 3: Evolution of natural uranium resources for the three scenarios considered.

Figure 4: Amounts of plutonium and 233U present in the fuel cycles of the reactors for the three scenarios considered.